Semiconductor laser

ABSTRACT

A die pad and a plurality of leads are integrally held by a resin portion made of mold resin, and a laser chip is mounted on the die pad through a sub-mount. The resin portion ( 2 ) has a base portion ( 21 ) that integrally holds the plurality of leads, and has a substantially round shape in an external shape thereof, and a die pad holding portion ( 22 ) that is continuously formed above the base portion, and holds the rear surface and the side portions of the die pad. The die pad holding portion has an external shape that is included inside a circle P having a diameter that is smaller than the outer diameter of the substantially round shape of the base portion. 
     Consequently, it is possible to provide an optical-disk-use semiconductor laser, such as CD-use and DVD-use semiconductor laser, which has the same structure as the can-type structure and an inexpensive resin package.

FIELD OF THE INVENTION

The present invention relates to a semiconductor laser having asmall-size structure easily manufactured at low costs, which is inparticular suitably applied to a pickup-use light source for use in CDs,DVDs (digital versatile disks), DVD-ROMs and data-writable CD-R/RWs.More specifically, the present invention concerns a mold-typesemiconductor laser that is different from the conventional can-typesemiconductor laser covered with a metal cap, achieves low costs byusing resin to form a package, and has a compatible structure so that itcan replace the conventional semiconductor laser without the necessityof changing the structure of an optical pickup.

BACKGROUND OF THE INVENTION

A conventional stem-type semiconductor laser to be used in a CD-usepickup and the like, which has been disclosed by, for example, JapanesePatent Application Laid-Open No. 2001-111152, has a structure as shownin FIG. 5. In other words, a metal material such as iron is formedthrough a cold forging method, and one portion of the center of a base61 is raised to form a heat sink portion 62 to which leads 63 and 65 aresecured through glass 66 or the like to form a stem 60, and a laser chip71 is mounted on this heat sink portion 62 through a sub-mount 74 madeof a silicon substrate and the like, with one of electrodes (on the rearside of the chip 71) being electrically connected to the lead 63 by awire 73 through a relay portion 78 of the sub-mount 74, while the otherelectrode is connected to the sub-mount 74 through the wire 73, so thatit is electrically connected to a common lead 64 via the heat sinkportion 62 and the base 61 through the rear surface.

Here, reference numeral 72 represents a monitor-use light-receivingelement one of electrodes of which is connected to the lead 65 throughthe wire 73, while the other electrode is electrically connected to thecommon lead 64 through the sub-mount 74, the heat sink portion 62 andthe base 61. Further, a cap 75 is put on the periphery thereof; thus,the semiconductor laser is formed. A through hole 75 a is formed in thecenter of the top portion of the cap 75 so that light, emitted by thelaser chip 71, is transmitted through it, and a glass plate 76 isattached thereto by using an adhesive 77 so as to seal the through hole.

As described above, with respect to the conventional semiconductor laserto be used in a pickup for a CD, a DVD and the like, a package having acan-type structure in which the leads 63, 64 and 65 are secured to themetal base 61 so that the laser chip 71 is secured to the heat sink 62connected to the base 61 has been mainly used. For this reason, thisstructure has good heat conduction, and also has a high airtightproperty with superior reliability since it is covered with the metalcap 75 on the periphery thereof; however, in this structure, since theleads 63 and 65 need to be sealingly bonded by using glass 66 or thelike, the resulting problems are that it is not possible to shorten thediameter of the stem 60, that a number of parts are required and thatcomplex manufacturing processes are required to cause high costs.

In recent years, along with the current cost reductions in electronicapparatuses including, in particular, personal computers, there havebeen strong demands for cost reduction also in semiconductor lasers tobe used for pickups and the like. For this reason, there have beendemands for improvements on the laser chip side in an attempt to improveresistance of the laser chip against external air, by using aninexpensive mold-type structure using a lead frame and a resin mold,which is completely the same structure as the conventional can-typestructure.

SUMMARY OF THE INVENTION

The present invention has been devised to solve the above-mentionedproblems, and its objective is to provide a semiconductor laser for usein a CD-use or DVD-use optical disk, which has not a can-type structure,but an inexpensive frame structure using a lead frame and a resin mold,and has the same structure as the conventional can-type structure sothat it can replace the conventional structure, as it is.

Another objective of the present invention is to provide a semiconductorlaser which, in spite of the fact that it has a characteristic in which,when molded by using a mold resin, the upper mold and the lower mold arenot completely coincident with each other so that a certain face with aparting line being interpolated in between, is not completely formedinto a predetermined plane, allows a laser chip to be positioned byusing a face formed by the mold resin as a reference face.

Still another objective of the present invention is to provide asemiconductor laser which can accurately carry out a precise positioningprocess and the like required for a semiconductor laser, and alsoprevents corrosion or the like to the lead frame so that highcharacteristics can be maintained.

In accordance with the present invention, a semiconductor laser isconstituted by a die pad and a plurality of leads formed by aplate-shaped lead frame, a resin portion made of a mold resin thatintegrally supports the die pad and the plurality of leads, and a laserchip that is mounted on one surface of the die pad, wherein the resinportion has a base portion that integrally holds the plurality of leads,with a substantially round shape in its external shape, and a die padholding portion that is continuously formed above the base portion, andholds the rear surface and the side portions of the die pad, with anexternal shape that is included inside a circle having a diametersmaller than an outer diameter of the substantially round shape of thebase portion. The die pad holding portion may be formed into a concaveshape in a plane shape when viewed from above, which has a bottom faceon the rear surface side of the die pad that is substantially flat andside portions so as to form a recessed portion at the die pad portion.

Here, the expression, “substantially round shape”, means that it is notnecessarily a true round shape and may be a shape close to the roundshape so as to be rotated, and may include a state in which concaveportions having various shapes are formed on the periphery of the roundshape, or a state in which one portion of the round shape is cut out toform a flat face.

The resin portion is formed through a die molding process that iscarried out with the rear surface of the lead frame serving as a partingline, and is preferably formed so that an upper surface of the baseportion which is exposed without the die pad holding portion beingformed thereon has a step difference between the surface side and therear-surface side of the die pad with bordering at the parting line. Ofexposed surfaces of the base portion having the step difference, only ahigher upper surface of the base portion having the step difference ispreferably used as a positioning reference upon mounting the laser chipand/or upon attaching the semiconductor laser to a pickup.

Surfaces of the plurality of leads and the die pad are silver-plated or3 layers-plated made of Ni/Pd/Au, and the resin portion is formed byusing super engineering plastic, more preferably, polyphthal amide or aliquid crystal polymer.

With this structure, the base portion of the mold resin is formed tohave the same shape as the conventional metal base, and although the diepad holding portion used for securing the die pad is formed to have aframe shape, since this frame-shaped die-pad holding portion is formedso as to be placed within a circle having the diameter smaller than theouter diameter of the substantially round-shaped base; therefore, thisshape is fitted to the conventional metal cap so that this can be dealtin the same manner as the conventional external shape with the metal capattached thereto. In other words, in the case when, upon actuallyassembling the semiconductor laser in a pickup or the like, apositioning process or the like is carried out, adjustments are madewhile rotating the semiconductor laser, and this structure makes itpossible to carry out the same rotation adjustments as the conventionalcan-type structure with a metal cap, and is dealt in the completely samemanner.

Here, a side face (a bottom face of the concave shape) of the die padholding portion on the die pad rear-face side is formed into a flatface; therefore, upon mounting a laser chip on the die pad, as well asupon electrically connecting the respective leads and electrodes of alaser chip or the like through wire bonding, the processes can becarried out while the flat face portion is maintained on the work benchso that the processes are easily carried out, while wire-bondingprocesses are carried out with high reliability. Further, the package isformed by using mold resin without using a metal base and a metal cap sothat manufacturing processes other than the wire-bonding processes canalso be carried out easily by using inexpensive materials, therebymaking it possible to reduce costs.

Moreover, by forming a step difference with respect to the heights ofthe base portion upper surfaces based upon the die mold parting line,that is, for example, when the rear surface of the die pad is theparting line, by forming the resin portion so as to make the baseportion upper surface on the surface side higher than the upper face onthe rear-surface side, a laser-chip positioning process and apositioning process in the case of assembling it in a pickup are alwayscarried out based upon the base portion upper surface on the die padside serving as a reference, without receiving adverse effects fromsurface irregularities caused by the parting line; thus, it becomespossible to carry out an accurate positioning process while forming apackage by using resin.

Furthermore, with respect to the material for the resin portion,super-engineering plastic, in particular, a polyphthalamide, a polyamide(PA; 9T nylon) or a liquid crystal polymer, is preferably used so thatit is possible to provide sufficient rigidity and also to form a shapewith high precision; thus, even in the case of manufacturing asemiconductor laser that requires very strict dimension and strength, itbecomes possible to satisfy these requirements, and also to preventcorrosion of silver plating to be applied to the leads and die-padsurface. In the case of mounting a laser chip and the like, it alsobecomes possible to carry out the mounting processes with highreliability and also to prevent degradation in electric characteristicsof a semiconductor laser; thus, the semiconductor laser of the presentinvention is desirably applied.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are front and plan explanatory views that show thestructure of one embodiment of a semiconductor laser in accordance withthe present invention;

FIG. 2 is an explanatory drawing that shows a lead frame to be used inthe semiconductor laser of FIG. 1;

FIG. 3, which is a side view of the semiconductor laser shown in FIG. 1,shows a step difference between an upper-mold base portion and alower-mold base portion in an exaggerated manner;

FIG. 4 is a block diagram that shows a structure in which a pickup isformed by using the semiconductor laser in accordance with the presentinvention; and

FIG. 5 is an explanatory drawing that shows a conventional semiconductorlaser of a can-type structure.

DETAILED DESCRIPTION

Next, referring to drawings, the following description will discuss asemiconductor laser in accordance with the present invention. As shownin FIGS. 1A and 1B that explain the front and top faces of oneembodiment of a semiconductor laser in accordance with the presentinvention, a die pad 11 a and a plurality of leads 11 to 13 formed by aplate-shaped lead frame are integrally held by a resin portion 2 made ofmold resin. A laser chip 4 is mounted on one face (a surface) of the diepad 11 a through a sub-mount 3. The resin portion 2 is constituted by abase portion 21 that integrally holds the plurality of leads 11 to 13and has a substantially round shape in its external shape and a die padholding portion 22 that is continuously formed above the base portion 21and holds the rear surface and side portions of the die pad 11 a. Thedie pad holding portion 22 has an external shape that is included withina circle P having a diameter smaller than the outer diameter of the baseportion 21 having substantially a round shape, with a side face (abottom face of the concave shape) B on the rear side of the die pad 11 abeing formed into substantially a flat face so that, when viewed fromabove, the die pad holding portion 22 has a concave shape with the diepad 11 a in a recessed section in a plane view.

The lead frame 1 is formed as follows; a plate member having a thicknessof about 0.4 mm, made of, for example, 42 alloy, copper or copper alloy,is subjected to a stamping molding process and the like as shown in FIG.2, and first to third leads 11 to 13 are secured to a side rail 17, witha die pad 11 a being formed on the tip of the first lead 11, and wirebonding portions 12 a and 13 a are respectively formed on the tips ofthe second and third leads 12 and 13; thus, a number of such sets areconnected to one another. After silver plating or 3 layers plating madeof Ni/Pd/Au has been applied to the lead frame 1 with the resin portion2 being formed thereon, the laser chip 4, etc. are assembled thereon asshown in FIG. 1A, and the respective leads 11 to 13 are cut off from theside rail 17 so that respective semiconductor lasers are separated.Here, reference numeral 18 represents an index hole.

The resin portion 2 is used for firmly securing the first to third leads11 to 13 so as not to be individually divided even when separated fromthe lead frame and for positively maintaining connections between therespective electrodes of a laser chip 4 or the like and the leads 11 to13, and formed by a resin-molding process using transfer mold and thelike. In the present invention, the base portion 21 and the die padholding portion 22 are formed so as to respectively correspond to a stemportion and a cap portion that covers the laser chip in the conventionalcan-package structure.

For this reason, the external shape of the base portion 21 is designedto have a shape similar to the external shape of the stem in theconventional structure, with an outer diameter of, for example, 5.6 mmφ,and a positioning-use cutout portion 25 and the like are formed on theperiphery thereof in the same manner as the conventional structure.Moreover, the base portion 21 is not necessarily formed as a completelyround shape (complete round) as shown in FIG. 1, and may have a flatface with a cutout portion, as indicated by C in FIG. 1B. That is, it isonly necessary for the base portion 21 to have substantially a roundshape in the same manner as the conventional stem so as to be rotated.

As shown in FIG. 1A, the die pad holding portion 22 extends upward fromthe base portion 21 in a manner so as to cover the rear surface and sideportions of the die pad 11 a, and the outer circumference thereof isformed so that it is allowed to enter the inside of a circle P(diameter: 3.2 mm) that corresponds to the outer diameter of theconventional metal cap, the circle P is coaxially with the outerdiameter of the base portion 21, with a diameter smaller than the outerdiameter thereof, while the side face B on the rear surface side of thedie pad 11 a is formed into a flat face. In this manner, the die padholding portion 22 is formed so that the external shape of the die padholding portion 22 is included within the circle P corresponding to theouter diameter of the conventional cap; thus, even when thesemiconductor laser of the present invention is used in a conventionalpickup device, it is possible to adjust the laser beam while beingrotated, in the same manner as the conventional semiconductor laser withthe can-type structure.

Moreover, since the side face B of the die pad holding portion 22 on therear surface side of the die pad 11 a is formed into a flat face, it iseasily housed inside the circle P, and upon mounting the laser chip 4and upon wire-bonding the laser chip 4 and the leads 12 and 13, it ispossible to firmly secure the die pad 11 a and consequently to carry outassembling processes easily.

As described above, since the resin portion 2 is formed by pouring resinwith the lead frame 1 being secured by a die, the border face (partingline) between the upper and the lower dies of the die is set on the leadframe, that is, on the surface of the die pad 11 a (surface on which thelaser chip is mounted) or on the rear surface thereof. In the exampleshown in FIG. 1, the parting line A is formed on the rear surface of thedie pad 11 a with the rear-face of the die pad 11 a being set as thedividing face of the die; however, in the present invention, asindicated by a side-face view in FIG. 3, the base portion 21 is moldedso that a step difference d of about 0.1 mm is provided between theupper-mold base portion (base portion on the lead frame surface side) 21a and the lower-mold base portion (base portion on the lead framerear-surface side) 22 b at a portion of the parting line A on the uppersurface D (surface on the side the die pad holding portion 22 isextended) of the base portion 21. The step difference of about 0.1 mmmakes it possible to always maintain the upper face D (see FIG. 3) ofthe upper-mold base portion 21 a higher without causing a reversedstate, even when a tolerance of about 0.05 mm is taken intoconsideration.

In other words, when the resin molding process is carried out with theupper die and the lower die being made face to face with each other, afine deviation tends to occur between cavities during a superposingprocess, with the result that the base-portion upper face derived fromthe upper die and the base-portion upper face derived from the lower dieare not formed into complete flat faces, causing a step difference andprotrusions formed on the joint faces. Since the semiconductor laserhaving the conventional can-type structure has a stem formed by a metalplate, no problem is raised with its flatness, and the stem is used as areference face for positioning or the like upon mounting the laser chipor upon assembling it in a pickup; however, when the package is formedby mold resin, a problem of deviations on the reference surface tends tooccur due to this problem with the parting line.

Therefore, in the present invention, the position of upper face D of thebase portion 21 is intentionally made different between the upper moldand the lower mold in such a manner that the base portion 21 ispreferably formed so that the upper face D of the upper-mold baseportion 21 a on the die-pad surface side is kept higher than the upperface of the lower-mold base portion 21 b by the above-mentioned lengthd. Here, the side that is kept higher is not necessarily the surfaceside of the die pad, and may be the rear-surface side, as long as a stepdifference is prepared.

Furthermore, the present invention features that the resin portion 2 ismade from super-engineering plastic, more specifically, a material suchas a polyphthal amide (PPA), a polyamide (PA; 9T nylon) or a liquidcrystal polymer (LCP). In other words, in the case when thesemiconductor laser of this type is formed by a package using moldresin, since a precise positioning process is required, it is necessaryto use a thermoplastic material with sufficient rigidity so that astrict dimension-measuring process is available without causing resinburrs and the like, and deformation is not caused by an external force.From the viewpoints of such preciseness and rigidity, conventionally,polyphenylene sulfide (PPS) has been used as an inexpensive materialwith sufficient rigidity; however, as a result of extensive researchefforts, the inventor of the present invention have found that in thecase of PPS, sulfur (S) forming one component thereof tends to reactwith Ag in silver plating formed on the surface of the lead frame tocause discoloration of the lead frame and the subsequent degradation inthe semiconductor laser characteristics (an increase in resistance ofthe joining face and the like).

The inventor of the present invention have subsequently found that theapplication of super-engineering plastic, such as PPA and LCP, makes itpossible to form a precise package without causing degradation in thecharacteristics of the semiconductor laser. In other words, in anattempt to form a semiconductor laser that requires a precise package tobe used for a pickup by using a package using a lead frame with silverplating applied thereto and mold resin, the application of normalmaterials causes problems with reliability; however, the application ofsuper-engineering plastic as the resin material makes it possible toprovide a semiconductor laser with high characteristics without causingthe above-mentioned problems.

The laser chip 4 is formed so as to have a normal double-heterostructure made from, for example, an AlGaAs-based or InGaAlP-basedcompound semiconductor, and has a size of about 250 μm×250 μm in thecase of a CD-use model, a size of about 250 μm×500 μm in the case of aDVD-use model, and a size of about 250 μm×800 μm the case of aCD-R/RW-use model. These sizes are very small, and in order to furtherprovide easiness in handling and ensure a heat-radiating property, thelaser chip is normally bonded to a sub-mount 3 that has a size of about0.8 mm×1 mm, and is made of a silicon substrate, an AlN (aluminanitride) substrate, or the like. Further, as shown in FIG. 1A, one ofthe electrodes, which is connected to the sub-mount 3 throughwire-bonding using a gold wire 6 or the like, is connected to the firstlead 11 from the rear surface thereof through the die pad 11 a by usinga conductive adhesive or the like, with the other electrode(rear-surface electrode) being connected to the second lead 12 via aconnecting portion 3 a on the sub-mount 3 through wire bonding by usinga gold wire 6 or the like.

Moreover, a light-receiving element 5, which is used for monitoring thelight-emitting power of the laser chip 4, is placed on the sub-mount 3in the same manner, and one of the electrodes is connected to the firstlead 11 through the sub-mount 3 and the die pad 11 a or the like, withthe other electrode being directly electrically connected to the thirdlead 13 through wire bonding by using a gold wire 6 or the like. Here,the light-receiving element 5 may be placed at a position different fromthe sub-mount 3, or the light-receiving element 5 may be omitted, if itis not necessary.

In accordance with the present invention, in a structure in which apackage using a lead frame and mold resin is used, the base portion andthe die pad holding portion are formed into shapes respectivelycorresponding to the stem and the cap of a conventional can-typestructure; therefore, this structure can replace the conventionalsemiconductor laser of the can-type structure so as to be used as it is.In particular, the die pad holding portion is formed so as to be housedinside the diameter of the conventional cap so that, upon actuallyassembling the semiconductor laser in a pickup, adjustments are madewhile rotating the semiconductor laser in the same manner as theconventional can-type structure. Moreover, since the side face on thedie-pad rear-surface side of the die pad holding portion is formed intoa flat face, mounting and wire-bonding processes for a laser chip andthe like can be carried out very easily, thereby making it possible toprovide a bonding process with high reliability.

Moreover, in accordance with the present invention, in the structure inwhich the base portion is formed by mold resin, a step difference isformed by the parting line at the height of the base portion so that thebase portion is formed so as to allow only one of the faces of theupper-mold base portion and the lower-mold base portion derived from theupper metal mold and the lower metal mold to serve as a reference face;therefore, it is possible to prevent deviations and irregularities onthe flat face caused by the parting line, and consequently to provide avery stable reference face and preciseness that is the same as orsuperior to a metal-plate stem of the conventional structure.

Moreover, by using super-engineering plastic as the resin materialforming the resin portion, it is possible to obtain a precise processingproperty and sufficient rigidity for stability againstexternally-applied forces, and consequently to provide a very stablesemiconductor laser without causing corrosion in the lead frame due toreaction of the lead frame with silver plating or the like.

FIG. 4 is an explanatory drawing that schematically shows a blockdiagram in which a thin pickup is formed by using this semiconductorlaser. In other words, a semiconductor laser 50 is placed laterally, andlight, directed from the semiconductor laser, is divided into threeportions by using a diffraction grating 51 through, for example, athree-beam method, and the resulting rays are formed into parallel lightbeams by using a collimator lens 53 through a beam splitter 52 thatseparates outgoing light and reflected light; thus, the resultingparallel light beams are bent by a prism mirror (reflecting mirror) 54by 90° (z-axis direction), and then focused on the surface of a disk 56such as a DVD and a CD by an objective lens 55. Further, light reflectedfrom the disk 56 is directed through a beam splitter 52, a concave lens57, etc., to a photo-detector 58 so as to be detected. Here, in FIG. 4,the semiconductor laser 50 and the photo-detector 58 are locatedsubstantially on the same face (xy face).

The above-mentioned description has been exemplified aone-wavelength-use structure with three leads; however, a structure withfour leads on which a two-wavelength-use laser chip is mounted may beused.

Although preferred examples have been described in some detail it is tobe understood that certain changes can be made by those skilled in theart without departing from the spirit and scope of the invention asdefined by the appended claims.

1. A semiconductor laser comprising: a die pad and a plurality of leadsformed by a plate-shaped lead frame; a resin portion, made of a moldresin, that integrally supports the die pad and the plurality of leads;and a laser chip that is mounted on one surface of the die pad, whereinthe resin portion has a base portion that integrally holds the pluralityof leads, and has a substantially round shape in an external shapethereof, and a die pad holding portion that is continuously formed abovethe base portion, and holds a rear surface and side portions of the diepad, and has an external shape that is included inside a circle having adiameter smaller than an outer diameter of the substantially round shapeof the base portion; wherein the resin portion is formed through a diemolding process that is carried out with one face of the lead frameserving as a parting line, and is formed so that an upper surface of thebase portion, which is exposed without the die pad holding portion beingformed thereon, has a step difference between a surface side and arear-surface side of the die pad which border at the parting line. 2.The semiconductor laser according to claim 1, wherein only a higherupper surface of the exposed surfaces of the base portion having thestep difference is used as a positioning reference upon mounting thelaser chip and/or upon attaching the semiconductor laser to a pickup. 3.The semiconductor laser according to claim 2, wherein the parting lineis formed on the rear surface of the lead frame, and the upper surfaceof the base portion on the surface side of the lead frame is used as thepositioning reference.
 4. The semiconductor laser according to claim 1,wherein the die pad holding portion is formed into a concave shape in aplane when viewed from above, which has a bottom face on the rearsurface side of the die pad that is substantially flat and side portionsso as to form a recessed portion at the die pad portion.
 5. Thesemiconductor laser according to claim 1, wherein a positioning-usecutout portion is formed on the periphery of the base portion.
 6. Thesemiconductor laser according to claim 1, wherein surfaces of theplurality of leads and the die pad are silver-plated or triplelayer-plated with Ni/Pd/Au, and the resin portion comprises superengineering plastic.
 7. The semiconductor laser according to claim 6,wherein the super engineering plastic is a polyphthal amide or apolyamide (PA) a liquid crystal polymer.
 8. A semiconductor lasercomprising: a die pad and a plurality of leads formed by a plate-shapedlead frame; a resin portion, made of a mold resin, that integrallysupports the die pad and the plurality of leads; and a laser chip thatis mounted on one surface of the die pad, wherein the resin portion hasa base portion that integrally holds the plurality of leads, and has asubstantially round shape in an external shape thereof, and a die padholding portion that is continuously formed above the base portion, andholds a rear surface and side portions of the die pad, and has anexternal shape that is included inside a circle having a diametersmaller than an outer diameter of the substantially round shape of thebase portion; wherein surfaces of the plurality of leads and the die padare silver-plated or triple layer-plated with Ni/Pd/Au, and the resinportion comprises super engineering plastic.
 9. The semiconductor laseraccording to claim 8, wherein the resin portion is formed through a diemolding process that is carried out with one face of the lead frameserving as a parting line, and is formed so that an upper surface of thebase portion, which is exposed without the die pad holding portion beingfarmed thereon, has a step difference between a surface side and arear-surface side of the die pad which border at the parting line, andwherein only a higher upper surface of the exposed surfaces of the baseportion having the step difference is used as a positioning referenceupon mounting the laser chip and/or upon attaching the semiconductorlaser to a pickup.
 10. The semiconductor laser according to claim 9,wherein the parting line is formed on the rear surface of the leadframe, and the upper surface of the base portion on the surface side ofthe lead frame is used as the positioning reference.
 11. Thesemiconductor laser according to claim 8, wherein the die pad holdingportion is formed into a concave shape in a plane when viewed fromabove, which has a bottom face on the rear surface side of the die padthat is substantially flat and side portions so as to form a recessedportion at the die pad portion.
 12. The semiconductor laser according toclaim 8, wherein a positioning-use cutout portion is formed on theperiphery of the base portion.
 13. The semiconductor laser according toclaim 8, wherein the super engineering plastic is a polyphthal amide ora polyamide (PA) a liquid crystal polymer.